Control mechanism for machines



y 1931- D. E. LEWELLEN ET AL ,155

CONTROL MECHANISM FOR MACHINES Fi led Oct. 8, 1928 low 5 DafcqELewellen EmmansFLewelIen Patented July 21, 1931 UNITED STATES PATENT. OFFICE DARGY EDWIN LEWELLEN AND EMMONS FREEMAN LEWELLEN, OF COLUMBUS, INDIANA CONTROL MECHANISM FOR MACHINES Application filed October 8, 1928. Serial No. 311,134.

This invention relates to controlling devices for controlling machines which grind or refine material to a comminuted form and is particularly adapted for controlling machines which grind and refine paper pulp, preparatory to its use in paper making. In paper mills the device which grinds and refines the pulp is known in the industry as a Jordan. Throughout this specification the word Jordan will be used to designate this grinding mill.

A general object of our invention is to provide a control device for controlling or adjusting a machine by variations in the power circuit, due to variations in the load on the motor, the variations in the load on the motor resulting from variations in the material supplied to the machine.

An object of this invention is toprovide means for controlling the grinding mill so as to compensate for variations in the consistency of the paper stock which is fed to the mill.

A further object of the invention is to provide a delicate controlling device which is electrically operated in which the contact points in the initial controlling circuit will.

be in contact only for an instant at the be X be obviated.

Further objects and purposes of the control device will become more apparent as details of the Jordan are more fully described.

Referring to the accompanying drawings which is made a part hereof and on which similar reference characters indicate similar parts,

Figure 1 is a view of the control circuits forming the subject matter of this invention, showing the refining engine in vertical sec tion, and

Figure 21s a diagrammatic showing of one of the switches.

In the drawings numeral 10 indicates the casing of a Jordan. casing and carried in bearings 11 and 12 is a shaft 13 to which is keyed a movable plug- 14. The shaft 13 is connected by means ofblades 21. The casing 10 is provided with an opening 22 through which the stock is fed to the mill. After passing through the mill and being ground the stock passes out through a pipe 23. The fineness to which the stock is cut depends on the spaces between the cutters 20 and 21. The plug 14 and the casing 10 are in the shape of the frustum of a cone. plug 14 therefore will vary the distance between the cutting knives. In order to adjust the plug in the casing we mount the bearing 11 so that it may slide on a base 24. A depending lug 25 on the bearing 11 is screw' threaded through which extends a threaded screw 26 having a manually operable wheel 27 on its outer end. Rotation of this wheel will move the bearing 11. The shaft 13 is secured in the bearing 11 so that it may freely rotate in the bearing but so that axial movement of the bearing will move the shaft along with it. Rotation of the wheel 27 therefore will adjust the plug 14 lengthwise of the casing 10 and vary the distance between cutters 20 and 21.

The consistency of paper stock, that is, the proportion between the amount of pulp in a given quantity of water is continually changing. If the knives 20 and 21 of the Jordan remain a fixed distance apart then when thick stock passes through the machine it will be ground much finer than it will when thin'stock passes through. The thin stock will pass through with practically no grinding action at all. If the stock is thin 3 it will actually pass through the mill with Extending through this no grinding at all consequently it'will have much, coarser fibers than the stock which passes through in a thicker solution. For

Axial movement of the this reason it is necessary to maintain an adjustment between the knives 20 and 21 that corresponds to the consistency of the stock which passes through the Jordan. The hand wheel provides an approximate adj ustment but this adjustment may have to be frequently changed and atbest is only an approximate correct adjustment for the particular time at which itis made. Our invention consists in providing an automatic adj ustment for the knives 20 and 21 which will correspond to changes in the consistency of the stock which passes through the Jordan.

It should be apparent that the load upon the motor 16 which drives the Jordan should correspond to the consistency of the stock which passes through the mill, that is, if the knife adjustment remains the same the motor will require much more current if the consistency of the stock is very heavy because at this time it is doing more grinding. If the stock changes so that it is a very thin solution the grinding cutters have practically nothing to do and consequently the load on the motor 16 suddenly drops. There is quite a variation in the power required between these two extremes. We make use of the variation in current to the motor 16 which drives the Jordan grinding machine to operate mechanism for controlling adjustment of the cutters.

Upon the shaft 26 is mounted a sprocket wheel 28 which is connected by means of a chain 29 with a sprocket 'wheel 30 upon a shaft 31. The sprocket wheel 30 is loosely mounted on the shaft 31 between collars 32 and 33. Upon the end of the shaft 31 is secured a nut 34. A compression spring 35 is mounted upon the shaft 31 between the nut 34 and collar 32. The collar 32 is splined to the shaft 31 but is permitted axial movement on the shaft. The sprocket is therefore frictionally held between the collars 32 and 33. The shaft 31 is driven by an electric motor 36. Greatly reduced earing is provided between the motor sha t and the shaft 31 in any conventional way so that, the shaft 31 will be driven at a very slow speed, when the motor is running at normal speed. Upon the motor casing adjacent the sprocket wheel 30 is mounted an idler arm 37 which carries an idle sprocket Wheel 38. The function of this sprocket wheel is to take up slack in the sprocket chain. The tension of the spring 35 may be varied bymeans of the nut 34 which is screw threaded upon the shaft 31.

The motor 16 is the usual three-phase motor which is driven 'by means of current taken from lead-in wires 39, 40 and 41 which enter a starting box 42 of conventional construction. lVires 43 and 44 lead directly from the starting box 42 to-the motor 16. The wire 45 on the starting box passes to a post 46 on a currenttransformer 47 A wire 48 passes from the transformer direct to the motor 16. The current transformer 47 is a well-known device. Wires 49 and 50 on the transformer pass to a coil in a control ammeter 51. The current passing through wires 49 and 50 is in direct proportion to the load on the wires 45 and 48. The transformer enables us to operate the ammeter with a much smaller total current than would be required'if the coil in the ammeter were directly in the line which passes from the control box 42 to the motor. Such transformers and the theory of their operation are wellknown and require no further description in this specification. The application of the ammeter to this controlling system will now be explained.

As just stated the coil in ammeter 51 has wires 49 and 50 passing therearound. An arm 52 is pivoted so as to be accurately balanced at 53. An arcuate lower portion of this arm extends adjacent the coil and provides an armature. It will be seen then that any variation in the load on the motor 16 by causing a variation in the current passing through the coil of the ammeter will cause a deflection in the arm 52. Positioned at each side of the arm 52 are arms 53 and 54 carrying contact points 55 and 56. The contact points are secured upon the ends of springs 55 and 56 which are fastened to the ends of the arms 53 and 54 respectively. The purpose of the spring will later be explained. These arms are pivoted at 53' and carry segmental gears 57 and 58 which mesh with pinions 59 and 60 on shafts 61 and 62. The shafts 61 and 62 are journaled in the plate which holds the ammeter and extend out through the front cover. These shafts moreover are slotted so they may be turned with a screw driver to position the contact points 55 and 56 toward and from the contact point on the arm 52. The purpose of this adjustment is to provide for different loads on the motor 16. In treating certain qualities of pulp of paper stock the opening between the paper knives is set different from what would be required for other qualities of stock so that the motor may be required to carry a uniform load, for example, of 100 amperes at one time while at other times it would carry a uniform load of 150 amperes. In making the adjustments the contact arms 53 and 54 are turned to the left and to the right away from ivoted arm 52 until the arm 52 controlleol by the ammeter reaches the position indicated by the load on the motor, for 100 amperes, if this is the load under which the motor is to operate. The contacts 55 and 56 are then moved near the position of the contact 52 so that any variation in the load on the motor will immediately bring contact 52 into engagement with contact 55 or 56.

The mechanism of the ammeter is very delicate and must be accurately balanced.

It is necessary therefore to protect it by an enclosed case as shown. In order to make adjustment more accurate we mount within the casing a small light at 57 which burns continually to light the inside of the am meter mechanism. This light has nothing to do with operation of the control system but is simply placed in this position for the convenience of the operator to enable him to make accurate adjustment without the use of other lights on the control system cabinet.

At 63 is a conditioning device for the control system which allows the control motor 36 to operate only during a short interval. This controller consists of a motor 64 which drives a shaft65 by means of a pinion 66 on the shaft and a gear 67 on the shaft 65. The shaft 65 carries a cam 68. On a shaft 69 is pivotally mounted a bar 70 which has a pin 71 extending out from one side and a pin 72 extending out from one side on the opposite end. The end carrying the pin 71 is much heavier therefore the pin' 71 will rest upon the surface of the cam 68. Pivotally mounted on the shaft 69 is also a bar 73 which carries at its end a contact point 74. The bar 73 normally rests upon the pin 72 in the bar 70. A. bar 75 is pivotally mounted at 76 on the frame of the device and carries at its forward free end a contact point 77. A shaft 78 has mounted thereon a disk 79 which carries a pin 80 upon which pin the end of the bar 75 rests. A pointer arm 81 on the disk indicates readings on a scale 82. Movement of pointer 81 will move pin 80 to move the contact point 77 toward and from the contact point 74.

In operation the motor 64 runs at a constant speed and runs continuously when the control system is in operation. It should be apparent therefore that the contacts 74 and 77 are brought into engagement at predetermined intervals since the cam 68 will raise the arm 70 to allow the contact point 74 to drop into engagement with the contact point 77 as the end of the arm passes over the highest point of the cam. The time during which 74 and 77 will remain together can be regulated by positioning the pointer 81 which controls the position of the contact point 77. The function of the above described device will become more apparent when its relation to the whole system has been more fully explained.

At 83 is shown a magnetic switch which is used to throw the control system into and out of operation by closing or opening the circuit from the control system to wires 43, 44 and 45. The switch 83 is operated by push buttons 84 and 84'. When the button 84 is pushed in against the resilient member carrying contact point 85 the circuit is closed through wire 87, contacts 85, 86, wire 88, coil 89, wire to wire 45 on the control box 42. This energizes the relay coil 89 to close the switch 83. When this switch is closed circuit passes from wire 87 through wire 91, contactpoint 92, contact 93, contact 94, contact 95, wire 88, coil 89, wire 90, back to wire 45 in the starting box. The coil 89 is then energized independently of starting button 84 and becomes a holding coil holding the switch 83 closed. To stop operation of the controlling system switch button 84' is pressed to break contact between points 94 and 95. This breaks the circuit through the coil 89 and de-energizes the coil and allows the switch 83 to open. Within the starting box 42 is provided suitable apparatus to stop the motor 16 due to an overload. This breaks circuit through the coil 89 and allows the switch 83 to open, likewise when the manually operable starting switch 96 is open circuit is broken through coil 89 so switch 83 is open. This provides mechanism whereby the control system will not begin operation until the starting button 84 has again been pushed in to close contact between 85 and 86 to energize the coil 89 and this coil will not be energized unless the circuit is closed to the main motor 16.

The system is provided with two relay switches shown at 96 and 97. The purpose of these relays is to close a circuit of a higher .amperage than that which may safely pass through the contact points 55, 52 and 56. The ammeter 51 is necessarily a very delicate instrument. For that reason the current passing through contact points 52, 55 and 56 must be very small. Relay coil 98 is connected in circuit with contact 55 and relay coil 99 is connected in circuit with contact 56. When contact point 52 is brought into engagement with contact-55 a circuit is formed as follows: Beginning with contact 55 it passes through wires 100 to relay coil 98, through wire 101 to contact point 77 on the-arm 75 through contact point 74, through wire 102, contact point 103, contact 104, wire 91 to wire 43 on the control box and through wire 45 on thecontrol box back through wire 90, contact point 105, contact 106, wire 107, contacts 108 and 109 on switch 110, through wire 111 to contact arm 52. WVhen this circuit is closed the relay coil 98 becomes energTzed and closes switch 96 to close contact v points 112 and 113. This then closes a circuit as follows: beginning with contact point 112 and following through wire 114 to coil 115, through wire 116 to contact point 77, through contact point-74, wire 102, con-.-

tact 103, contact 104, wi're91 to wire 43 on the control box 42 and through wire 45 on -the' control box back through wire 90, conbrings together contacts'118 and 119, 120 and 121, 122 and 123.

Shown at 124 is another relay coil and a relay switch 110. This switch diifers from those previously described in that it is closed when the coil 124 is not energized. When this coil becomes energized the switch is open. When the switch 117, just described, is closed it completes a circuit from contact point 122 on the switch 117 through coil 124, wire 102, contact 103, contact 104, wire 91 to wire 43 on the control box 42 and from wire 45 on this control box back through wire 90, contact 105,.contact 106, wire 125, wire 126 to contact 123. This instantly energizes the coil at 124 and opens the switch 110 to break contact between 108 and 109. This action breaks the circuit between contact arm 52 and contact 55, since the contact points 108 and 109 are a part of the circuit which is closed by engagement of points 55 and arm 52. The purpose of the relay coil 124 and switch 110 just described is to prevent welding of the contact point on arm 52 and contact 55 in case they should be held in together for any great length of time. By the action just mentioned any danger of welding the contact points 52, 55 and 56 is minimized since the circuit is passing through these contacts only instantly for the closing of the relay 98 instantly closes switch 117, and the closing of the switch 117 instantly breaks circuit through the contact points 108 and 109.

When the switch 117 is closed there is a circuit closed through the following line, beginning with contact point 120, through switch coil 115, wire 116, contact 77,'contact 74, wire 102, contact 103, contact 104, wire 91, wire 43 on the control box 42, and back through wire 45, wire 90, contact 105, contact 106, wire 125, wire 126 to contact point 121 opposite contact point 120,thus maintaining a circuit through the coil 115 to hold'the switch 117closed. So long as the contacts 74 and 77 are held in engagement the switch 117 will remain closed, since the coil 115 is energized. When the switch 117 is closed there is another circuit passing through the line as follows: Beginning with contact point 118 the circuit is closed through coil 127, wire 128, wire 129 to contact 130, contact 131, wire 132 to wire 44 on the switch box 42 and back through wire 45 on the said switch box, wire 90, contact 105, contact 106, wire 125, wire 126, to contact point 119 opposite contact point 118. Closing of this circuit energizes the coil at 127 to close the relay switch 133.

From the description so far given it will be seen that energizing the coil 115 and closing the switch 117 serves three purposes,- first, closing contacts 122 and 123 closes the circuit to operate the relay 124 which breaks the contact between points 108 and 109, and

breaks the circuit through the ammeter contact arm 52 and contact 55 or 52 and 56 as will later appear ;second, closing the switch 117 closes contacts 120 and 121 to close the circuit through the switch coil 115 to make of this a holding coil; and third, energizing the coil 115 and closing the switch 117 closes the circuit through the coil 127 to operate the relay switch 133.

When the switch 133 is closed three circuits are formed, beginning with wire 43 on the control box 42, the circuit is closed through wire'91, contact 104, contact 103, wire 134, contact 135, contact 136, wire 137 to the motor 36. A circuit is also closed from wire 44 on the-control box 42, through contact 131, contact 130, wire 138, contact 139, contact 140, wire 141 tothe motor 36. A third circuit is closed through wire 45 on the control box 42, wire 90, contact 105, contact 106, wire 125, contact 142, contact 143, wire 144 to the motor 36. These circuits being closed the motor 36 will operate so long as the controller'contacts 74 and 77 are together. Since the motor 64 runs continuously the contact points 74 and 77 are being brought together and separated at regular ,intervals, and the duration of time during which they are in engagement is dependent upon the position of the pin 80 on the disk 79. With the motor running at a constant speed the indicating dial 82 may be so graduated that the pointer 81 will indicate the length of time during which contacts 74 and 77 will be in engagement.

It should be kept in mind that while the contact points 74 and 77 are constantly being brought together and separated there will be no action of the control system unless at the same time contact arm 52 and contact point 55 or 56 are in engagement. That is to say, as long as the motor 16 is operating on a load which holds the contact arm 52 out of engagement with the contact 55 or the contact 56 the control system does not function.

The operation as above described applies to a condition where arm 52 was brought into engagement with contact .55. When the load on the motor 16 varies in the reverse direction the contact arm 52 will be swung into' engagement with the contact 56.

This closes a circuit from arm 52 through wire 111 to contact point 109 through eon tact point 108 throughwire 107, contact 106, contact 105, wire 90 to wire 45 on the control box, and back through wire 43, on the control box 42, wire 91, contact 104, contact 103, through wire 102 to contact 74, contact 77, wire 145 to coil 99 through wire 146 to contact point 56. This energizes the coil 99 and closes the switch 97 to bring together contacts 147 and 148. A circuit is then closed as follows: Beginning with contact wire 152 to contact 77 through contact 74, through wire 102, contact 103, contact 104, wire 91, to wire 43 on the control box 42 and back through wire 45 on the control box, through wire 90, contact 105, contact 106, through wire 107 to contact 147. The circuit is then closed to energize coil 151 to close relay switch 153. Closing the switch 153 brings together contacts 154 and 155, 156 and 157,158 and 159. Circuits are then formed as follows: Beginning with contact 154 the circuit is closed through wire 163 to.

coil 124, through wire 102, contact 103, contact 104, wire 91, to wire 43, on the control box 42, and back through wire 45, wire 90, contact 105, contact 106, wire 125, wire 126, to contact 155 opposite contact 154. This closes the circuit on the relay 124, and as above described opens the switch 110 to disengage contact points 108 and 109 to break the circuit through the contact arm 52 and contact 56. Closing of switch 153 also closes a circuit as follows :beginning with contact point 156, through switch coil 151, wire 152, contact 77, contact 74, wire 102, contact 103, contact 104, wire 91, to wire 43 on control box 42, back through wire 45, wire 90, contact 105, contact 106, wire 125, wire 126, to contact point 157 opposite contact point 156, thus maintaining a circuit through the coil 151 to hold the switch 153 closed. So long as the contacts 74 and 77 are held in engagement the switch 153 will remain closed since the coil 151 is energized.

Another circuit is formed by closing the switch 153 which is as follows: beginning with contact 158, through coil 160, wire 161, wire 138, contact 130, contact 131 to wire 44 on the control box 42, and back through wire 45, wire 90, contact 105, contact 106, wire 125, wire 126, contact 159, opposite contact 158. From the description so far given it will be seen that energizing the coil 151 and closing the switch 153, serves three purposes ;first, closing the contacts 154 and 155 closes the circuit to operate the relay 124 and breaks the contact between points 108 and 109, and breaks the circuit through the ammeter contact arm 52 and the contact 56. Second, closing the switch 153 closes contacts 156 and 157 to close the circuit through the switch coil 151 to make this a holding coil ;--and third, energizing the coil 151 and closing the switch 153 closes the circuit through the coil 160 to operate the relay switch 162. This circuit energizes the coil 160 to close the relay switch 162, to close contacts 164 and 165, 166 and 167, and 168 and 169. Closing these contacts closes circuits as follows: beginning with wire 45 on the control box, through wire 90,

' contact 105, contact 106, wire 125, contact 165, contact 164, wire 137, to the motor 36.

Another circuit is closed from wire 44 on the control box 42, through contact 131, contact 130, wire 138, contact 167, contact 166, wire 141, to the motor 36. A third circuit is formed from the wire 43, on the control box 42, through wire 91, contact 104, contact 103, wire 134, contact 169, contact 168, wire 144, to the motor 36. The motor 36 is therefore operated by three-phase current from the starting box 42. It should be observed that in this instant current passes through wires 144 and 137 in the direction the reverse of that described in the previous operation of the motor 36 when the relay Switch 133 was closed. The motor 36 will therefore be driven in a direction reverse to that in which it was driven when contacts 52 and 55 were together. Consequently the plug 14 will be moved in a direction opposite from that in which it was moved before.

In connection with the switch 110 it should be observed that the control mechanism operates independently of the conso that the circuit established through con- 7 tacts 52 and 55 is no longer active in the operation. If, therefore, the contact arm 52 is swung to engage contact 56 while the motor 36 is operating this will not afiect operation of the motor for the relay switch coil is energized independently of the contacts on the ammeter. As soon as the circuit has been broken between contact points 74 and 77 the motor 36 will be stopped and will not start again until contact points 74 and 77 are again in engagement, and contact arm 52 comes into engagement with contact point 55 or 56.

The structure by which current through contact points 52 and 55 or 52 and 56 is allowed to pass for only an instant to prevent welding has been described. While the structure is suflicient to prevent welding we have sometimes found that these points would stick together even though they did not weld. It was necessary therefore to provide means for positively separating these contacts. This is done by passing an additional coil 170 around the ammeter 51. The main coil of the ammeter 51 is connected in series through wires 49 and 50 with the transformer 47. The new circuit through the coil 170 is formed as follows: In addition to the contacts already described the switch 117 has an arm switch is closed. The arms 171 and 173 are joined by a wire 184.

The back of the arm 136 on the switch 133 has an insulating block 175. A plate 17 6 is secured to this block. At 177 is a stationary plate against which the plate 17 6 rests when the switch is open. This struc ture is diagrammatically shown in Figure 2. The arm 164 on the switch 162 has an insulation block, a plate 179 and stationary rest plate 180 that correspond to those on the switch arm 136. The plates 176 and 179 are joined by a wire 181. A wire 182 leads from the coil 170 to the back plate 177, and wire 183 leads from the other side of the coil 170 to a wire 129. A wire 185 leads from the back plate 180 to the wire 184. It will be seen from the foregoing that the circuit through the coil 170 is closed only when both of the switches 133 and 162 are open and when either of the switches 117 or 153 is closed. Closing of switch 117 therefore performs a fourth function in ading the spring 56.

dition to the three previously described namel it closes a circuit as follows: from arm 1 1 through wire 184, wire 185, plate 180, plate 179, wire 181, through plate 176, plate 177, wire 182, coil 170, wire 183, contacts 130, 131, wire 132 to wire 44 on the control box, and back through wire 45, wire 90, contact arm 105, contact 106, wire 125,.

wire 126 to contact 172. Closin ,of switch 153 closes a circuit from arm 1 3 through the circuit just described to contact 174. This energizes the coil 170 which acts as a solenoid to exert a pull on the arm 52 to swing the upper end to the right. If contacts 52 and 55 are in engagement they will be forcibly separated. If contact 52 is in engagement with contact 56 the arm 52 will be pulled further toward arm 54 compress- When the spring rebounds it throws the contact 52 away from contact 56. Inasmuch as the circuitv through the coil 170 passes through contacts 179 and 180 on switch 162 and 176 and 177 on switch 133 the closing of either of these switches breaks the circuit through the coil and allows the contact 52 to assume the position corresponding to the load on the motor as this load affects the coil 51. Inasmuch as coils 115 and 151 are holding coils and continue energized until contacts 74 and 77 I Since the grinding cutters 20 and 21 have to be frequently renewed it is necessary that the casing 10 be easily opened to remove the with a cover which may be easily removed and the plug 14 moved to the left along with the bearing element 11. In order to make its removal easy we have provided the idle arm 37 which carries the idler pulley 38. The idler pulley is swung out of engagement with the sprocket chain 29 whereupon the chain may be readily removed from the sprocket wheel and the bearing 11 together with the plug 14 removed from the casing 10 andthe cutters 2O replaced by new or sharp ones.

While we have shown and described this machine as applied particularly to a paper pulp grinding machine, we wish it distinctly understood that the invention is not limited to this particular use. It obviously may be applied to any machine or process in which it is desirable to control some phase of the process by variations in the load on the m0- as to operate in a difierent manner and yet accomplish the same result. Essentially the invention consists of means for controlling a machine or process from variations in the current or load on a driving motor. Means for carrying out this means may vary, and the specific system which we have shown is believed to be one of the best which we now know, but in which changes may be made as experience suggests, without departing from the spirit of the invention.

It will be obvious to those skilled in the art that various changes may be made in our device without departing from the spirit of the invention and therefore we do not limit ourselves to what is shown in the drawings and described in the specification, but only as indicated in the appended claims.

Having thus fully described our said invention, what we claim as new and desire to secure by Letters Patent, is:

1. A control device for a mechanism for operating upon work comprising a motor for'driving said mechanism and a device responsive to variations in the load on said motor for adjusting the said mechanism, substantially as set forth.

2. In a machine for grinding and refining material to a comminuted condition having an electric motor for driving-the same, a control device responsive to variations in the load on said motor in control of mechaplug 14. The casing is therefore provided nism for varying the said grinding and refining machine to grind the material to a finer or coarser degree, substantially as set forth.

3. A control system for a grinding and refining machine comprising a grinding and refining engine, a motor for driving the same, an ammeter responsive to variations in the load of said motor in control of means for adjusting the said grinder to grind finer or coarser material, substantially as set forth.

4. A controlsystem for a grinding and refining engine comprising a grinding and refining mill, an electricmotor for driving the same, anammeter responsive to variations in the load on said motor, a motor for adjusting the said grinding mill to grind finer or coarser material, the said motor being controlled by the said ammeter, substantially as set forth.

5. A control system comprising a grinding and refining mill, a motor for driving the same, an ammeter responsive to variations in the load on the said motor, a motor for drivingmeans for adjusting the said mill to grind work to a finer or coarser degree, the said last named motor being controlled by the said ammeter, and means whereby the said last named motor will operate only for a predetermined duration, substantially as set forth.

6. A control system comprising a mill for grinding and refining work, a motor for driving the same, an ammeter responsive to variations in the load on the said motor, a motor for driving means for adjusting the said mill to grind the work to a finer or coarser degree, the said last named motor being controlled by the said ammeter, a conditioning means whereby the said last named motor will operate only for a predetermined duration, and means for changing the duration, substantially as set forth.

7. A control system comprising a mill for grinding and refining work, a motor for driving the sa me, an ammeter responsive to variations in the load on the said motor, a motor for driving means for adjusting the said mill to grind the Work to a finer or coarser degree, the said last named motor being controlled by the said ammeter, a conditioning means whereby the said last named motor will operate only for a predetermined duration, and means for instantly breaking the circuit closed by the said ammeter, substantially as set forth.

8. A control system comprising a mill for grinding and refining work, a motor for driving the same, an ammeter responsive to variations in the load on the said motor, a motor for driving means for adjusting the said mill to grind the Work to a finer or coarser degree,'the said last named motor being controlled by the said ammeter, a conditioning means whereby the said last named motor will operate only for a predetermined duration, and means for operating the said motor by a circuit independent of the circuit closed by the said ammeter.

9. In a system for controlling a refining and grinding engine, a motor for driving the said engine, a transformer, an ammeter controlled by the said transformer and operable in response to variations in the load on the said motor, and means for adjusting the ammeter to render it responsive to a predetermined variation in the load on the motor, substantially as set forth.

10. In a paper pulp refining and grinding machine a control device responsive to variations in the load on the machine, and controlling means for adjusting the grinding elements in the machine, substantially as set forth.

a 11. A paper stock grindingmachine comprising a casing having cutting blades mounted therein, a plug mounted in said casing having cutters mounted thereon to cooperate with those in the casing, a motor for rotating said plug, means for adjusting said plug to vary the distance between the cutters on the plug and those in the casing, and means responsive to variation in the load on.

the said motor due to variations in the consistency of the material fed to the machine for controlling said adjusting means, substantially as set forth.

12. In a paper stock grinding machine, means operable by variations in the consistency of thestock which passes through the machine in control of means for adjusting the relative position of the grinding elements in the machine, and means limiting the operation of the said control means to predetermined intervals and predetermined durations, substantially as set forth.

13. In a paper stock grinding machine, means operable by variations in the consistency of the stock which passes through the machine in control of means for adjusting the relative position of the grinding elements in the machine, means limiting the operation of the said control means to predetermined intervals and predetermined durations, and means for varying the said durations, substantially as set forth.

14. A machine for grinding material comprising cooperative grinding elements, a motor for driving said elements, means responsive to variations in the load on the motorfor adjusting said grinding elements toward and from each other, substantially as set forth.

15. In a paper stock grinding machine, a mill for grinding stock, a motor for driving said mill, means responsiveto an overload on said motor for adjusting the grinding elements away from each other whereby'the stock will be uniformly ground as the consistency of the stock thickens, substantially as set forth.

16. In a paper stock grinding machine, grinding elements, a motor for driving said grinding elements, means responsive to an underload on said motor for -moving the grinding elements toward each other to grind the stock to a uniform degree of fineness when the consistency of the stock bewcomes thinner, substantially as set forth.

3 17. In a paper making machine, means for grinding the paper stock, a motor for driving said means, means for adjusting the said grinding means to grind stock of different consistencies, and automatic means for controlllng sald adjustlng means 1n response to variations in the load on said F energizing circuit for operating said mechanism, and means for instantly breaking the separate circuit when it has erformed its function, substantially as set orth.

19. A controlling system comprising a machine for operating on work, a motor for driving said machine, a contact making mechanism for controlling contacts in a circuit separate from the mechanism energizmg circuit, an energizing circuit for operating said mechanism, means for instantly breaking the. separate circuit when it has performed its function, and separate means for positively disengagin the contact points in said contact maklng mechanism, substantially as setforth.

20. machine for reducing material to a comminuted form comprising a grindin mlll, a motor for driving said mill, an means for controlling the mill by variations in the current or load on the motor, substantially as set forth.

21. A machine for reducing material to a comminuted form comprising a mill, a

motor for driving said mill, a circuit responsive to variations in the current on the motor for operating means for controlling a circuit which causes adjustment of the said mill, and means for instantly breaking the last .named circuit after it has performed 1ts function, substantially as set forth..

22. machine for reducing material to a comminuted form comprising a grinding mill, a motor for driving said mill, a circuit responsive to variations in the load on said motor for operating means for controlling a second circuit which causes adjustment of the' grinding elements in said mill, means for breakin said second circuit and for closin an auxi 'ary circuit when the said second circuit has performed its function, substantially as set forth.

23. A machine for reducing material to a comminuted form comprising a grinding mill, a motor for operating said mill, an 1 ing elements in said mill, a circuit for controlling the said last named circuit, but being normally ope-n, a circuit responsive to. variations in the load on the motor for closing the said last named circuit to operate the circuit which controls the grinding elements, and means for instantly and positively breaking said circuit after it has performed its function of energizing the circuit which controls the grinding elements substantially as set forth,

25. A controlling system having a plurality of electric circuits, a device for controlling contacts in said circuits, said controlling device having means for engaging said contacts at regular intervals and for predetermined durations of time, substantially as set forth.

26. A controlling system having a plurality of electric circuits, a device for controlling contacts is said circuits, said controlling device having means for engaging said contacts at regular intervals, means for engaging contacts for predetermined durations of time, said durations being adjustable, substantially as set forth. 27. A controlling system having a plurality of electric circuits, a device for controlling contacts in said circuits, said controlling device having means for engaging said contacts at regular intervals and for predetermined durations of time, means for adjusting the length of said durations and means for indicating the length of time of said durations, substantially as set forth.

28. A controlling system for a grinding machine comprising a grinding machine, a motor for drivingthe same and a mechanism responsive to variations in the load of said motor in control of means for adjusting the said grinder to grind materials to a finer or coar'serdegree, substantially as set forth.

29. A controlling system for a machine operating on material comprising a grinding mill, a motor for driving the same and a mechanism responsive to variations in the any wel load of said motor in control of means for adjusting the mill to produce predetermined quality of material, substantially as set forth.

30. In a system for controlling a grinding machine, a motor for driving said machine, an ammeter responsive to variations in the load on the said motor, and means for ad justing the ammeter to render it responsive to a predetermined load on the motor.

31. In a paper pulp refining and grind ing machine having a stationary element and a movable element adjustable toward or from the stationary element, a controlling device in control of means for moving the movable element toward or from the stationary element, the said control device being controlled in response to variations in the load on the machine, substantially as set forth.

32. A control device for a mechanism for operating upon work comprising a motor for driving the mechanism, means responsive to variations in the load on the said motor for adjusting said mechanism, and means for rendering the device responsive to predetermined loads on the motor, substatially as set forth. 33. The combination with a processing machine of a contact engaging device responsive to changing conditions of the processing, contacts carried by said device for opening and closing circuits adapted to control the processing, means for operating the contact device to close the said circuits and separate means for disengaging the said contacts, substantially as set forth.

34. In combination a' processin machine, a. motor for driving the mac ine, a contact engaging device connected to the said motor and responsive to changing conditions of the processing, circuits for conpoints of contact after the circuit through the contact points is broken, substantially as set forth.

37. In a processing machine of the kind described, a contact carrying device for controlling the processing, and means for moving the contact points relative to each other to break welds which form between them after the circuit through the contact points has been broken, substantially as set forth.

In witness whereof, we have hereunto set our hands at Columbus, Indiana this 4th day of September, A. D. nineteen hundred and twenty-eight.

DARCY EDWIN LEWELLEN.

EMMON S FREEMAN LEWELLEN.

trolling the said processing, contacts for opening and closing said circuits, and separate means for positively disengaging the contacts to break any weld which may have formed between them, substantially as set forth.

35. In combination a processing machine, a contact en aging device responsive to changing con itions of the processing, contacts carried by said device for opening and closing circuits for controlling the processing machine, and means for operating the contact device, and separate means for causing relative movement between the contacts to break any weld which may have formed at these contacts, substantially a set forth.

36. In combination a processing machine, a motor for driving said machine, a con tacting device responsive to variations in the load on the motor, contacts on said device, a se arate electric circuit for breaking which may have formed at the 

